Grease Pencil: customize the eraser as of in the old versions
The soft eraser now has two new parameters:

Affect Stroke Strength and Affect Stroke Thickness. These parameters define how the eraser affect the opacity and the thickness. The old eraser only affected the thickness, and the new default parameters affect the opacity (strength) in a 100% and the thickness in a 10%, so the stroke gets less and less opacity and the thickness is reduced in a small proportion (10%). We set this values after a lot of test to get the feeling of erasing in a paper.

If you want back to the "old" soft eraser, just set the Stroke Strength to 0% and the Stroke Thickness to 100%.

With these parameters you can configure the "feeling" of the eraser.